CO2 separation system for installation in vehicle using internal combustion engine as power source

ABSTRACT

The CO 2  separation system performs, when the internal combustion engine is operating and the vehicle is travelling, a first mode wherein exhaust gas generated by the internal combustion engine is introduced to a CO 2  supply side of a first CO 2  separation device via a first CO 2  supply side introduction flow path, and air from outside the vehicle is introduced to a CO 2  permeation side of the first CO 2  separation device via a first CO 2  permeation side introduction flow path using travelling wind, whereby CO 2  in the exhaust gas selectively permeates from the CO 2  supply side to the CO 2  permeation side of the first CO 2  separation device through a CO 2  permeable membrane of the first CO 2  separation device using a difference in CO 2  partial pressure between the CO 2  supply side and the CO 2  permeation side of the first CO 2  separation device as a driving force.

FIELD

The present invention relates to a CO₂ separation system for installation in a vehicle which uses an internal combustion engine as a power source.

BACKGROUND

It is known that the exhaust gasses of vehicles including internal combustion engines include components such as NO_(X), CO, and CH. These components are conventionally converted to N₂, CO₂, H₂O, etc., by an exhaust gas purification catalyst to purify the exhaust gas generated by the internal combustion engine and are discharged to the outside of the vehicle.

Among the gasses discharged to the outside of the vehicle, CO₂ is believed to contribute to the greenhouse effect, and reduction of the discharge amount thereof has been demanded.

Patent Literature 1 discloses capturing CO₂ from the exhaust flow of an internal combustion engine and temporarily compressing the CO₂ to increase the density thereof until it is discharged at a collection station during refueling of the vehicle.

Furthermore, Patent Literature 2 discloses reducing the CO₂ discharge of a vehicle by separating water and CO₂ from exhaust gas with a membrane separator and converting the CO₂ into a hydrocarbon fuel.

CITATION LIST Patent Literature

[PTL 1] Japanese Unexamined Patent Publication (Kohyo) No. 2015-510991

[PTL 2] Japanese Unexamined Patent Publication (Kohyo) No. 2015-502474

SUMMARY Technical Problem

From the viewpoint of reducing the CO₂ discharge of a vehicle, in vehicles using an internal combustion engine as a power source, it is desired to efficiently separate CO₂ in exhaust gas and recover the CO₂.

Furthermore, in general, it is believed that the concentration of CO₂ in the atmosphere around highly-trafficked roadways is higher than the atmosphere in other areas. Thus, if CO₂ in the atmosphere around these roadways can be reduced, environmental impact can be further reduced.

The present disclosure provides a CO₂ separation system which can efficiently separate CO₂ in the exhaust gas of vehicles using an internal combustion engine as a power source and CO₂ in the atmosphere around roadways.

Solution to Problem

The present inventors have discovered that the above problems can be solved by the following means:

<Aspect 1>

A CO₂ separation system for installation in a vehicle using an internal combustion engine as a power source, wherein the system comprises:

the internal combustion engine,

a first CO₂ separation device comprising a CO₂ permeable membrane separating a CO₂ supply side and a CO₂ permeation side,

a first CO₂ supply side introduction flow path for introducing exhaust gas generated by the internal combustion engine to the CO₂ supply side of the first CO₂ separation device, and

a first CO₂ permeation side introduction flow path for introducing air from outside the vehicle to the CO₂ permeation side of the first CO₂ separation device; and wherein the system:

(A) performs, when the internal combustion engine is operating and the vehicle is travelling, a first mode wherein exhaust gas generated by the internal combustion engine is introduced to the CO₂ supply side of the first CO₂ separation device via the first CO₂ supply side introduction flow path, and air from outside the vehicle is introduced to the CO₂ permeation side of the first CO₂ separation device via the first CO₂ permeation side introduction flow path using travelling wind, whereby CO₂ in the exhaust gas selectively permeates from the CO₂ supply side to the CO₂ permeation side of the first CO₂ separation device through the CO₂ permeable membrane of the first CO₂ separation device, using a difference in CO₂ partial pressure between the CO₂ supply side and the CO₂ permeation side of the first CO₂ separation device as a driving force.

<Aspect 2>

The system according to aspect 1, wherein the system further comprises:

a first decompression device for decompressing the CO₂ permeation side of the first CO₂ separation device; and wherein the system:

(B) performs, when the internal combustion engine is operating and the vehicle is stopped, a second mode wherein exhaust gas generated by the internal combustion engine is introduced to the CO₂ supply side of the first CO₂ separation device via the first CO₂ supply side introduction flow path and the CO₂ permeation side of the first CO₂ separation device is decompressed by the first decompression device, whereby CO₂ in the exhaust gas selectively permeates from the CO₂ supply side to the CO₂ permeation side of the first CO₂ separation device through the CO₂ permeable membrane of the first CO₂ separation device, using a difference in CO₂ partial pressure between the CO₂ supply side and the CO₂ permeation side of the first CO₂ separation device as a driving force.

<Aspect 3>

The system according to aspect 1 or 2, wherein the system further comprises:

a second CO₂ separation device comprising a CO₂ permeable membrane for separating a CO₂ supply side and a CO₂ permeation side,

a second CO₂ supply side introduction flow path for introducing air from outside the vehicle to the CO₂ supply side of the second CO₂ separation device, and

a second decompression device for decompressing the CO₂ permeation side of the second CO₂ separation device, wherein the system:

(C) performs, when the internal combustion engine is stopped, a third mode wherein air from outside the vehicle is introduced to the CO₂ supply side of the second CO₂ separation device via the second CO₂ supply side introduction flow path, and the CO₂ permeation side of the second CO₂ separation device is decompressed by the second decompression device, whereby CO₂ in the air selectively permeates from the CO₂ supply side to the CO₂ permeation side of the second CO₂ separation device through the CO₂ permeable membrane of the second CO₂ separation device using a difference in CO₂ partial pressure between the CO₂ supply side and the CO₂ permeation side of the second CO₂ separation device as a drive force.

<Aspect 4>

The system according to aspect 1, wherein the system further comprises:

a first decompression device for decompressing the CO₂ permeation side of the first CO₂ separation device,

a second CO₂ separation device comprising a CO₂ permeable membrane for separating a CO₂ supply side and a CO₂ permeation side,

a second CO₂ supply side introduction flow path for introducing air from outside the vehicle to the CO₂ supply side of the second CO₂ separation device, and

a second decompression device for decompressing the CO₂ permeation side of the second CO₂ separation device, wherein the system:

(B) performs, when the internal combustion engine is operating and the vehicle is stopped, a second mode wherein exhaust gas generated by the internal combustion engine is introduced to the CO₂ supply side of the first CO₂ separation device via the first CO₂ supply side introduction flow path and the CO₂ permeation side of the first CO₂ separation device is decompressed by the first decompression device, whereby, CO₂ in the exhaust gas selectively permeates from the CO₂ supply side to the CO₂ permeation side of the first CO₂ separation device through the CO₂ permeable membrane of the first CO₂ separation device using a difference in CO₂ partial pressure between the CO₂ supply side and the CO₂ permeation side of the first CO₂ separation device as a driving force, and

(C) performs, when the internal combustion engine is stopped, a third mode wherein air from outside the vehicle is introduced to the CO₂ supply side of the second CO₂ separation device via the second CO₂ supply side introduction flow path, and the CO₂ permeation side of the second CO₂ separation device is decompressed by the second decompression device, whereby, CO₂ in the air selectively permeates from the CO₂ supply side to the CO₂ permeation side of the second CO₂ separation device through the CO₂ permeable membrane of the second CO₂ separation device using a difference in CO₂ partial pressure between the CO₂ supply side and the CO₂ permeation side of the second CO₂ separation device as a drive force.

<Aspect 5>

The system according to aspect 4,

wherein the first CO₂ separation device and the second CO₂ separation device are identical,

wherein the first CO₂ supply side introduction flow path and the second CO₂ supply side introduction flow path are identical, and

wherein the first decompression device and the second decompression device are identical.

<Aspect 6>

The system according to any one of aspects 1 to 5, wherein the vehicle is a hybrid vehicle further comprising an electric motor, wherein at least one of the internal combustion engine and the electric motor is switched on and used as a power source.

Advantageous Effects of Invention

According to the present disclosure, a CO₂ separation system which can efficiently separate CO₂ in the exhaust gas of a vehicle using an internal combustion engine as a power source can be provided.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view of an example of a portion of the CO₂ separation system of the present disclosure performing a first mode.

FIG. 2 is a schematic view of an example of a portion of the CO₂ separation system of the present disclosure performing a second mode.

FIG. 3 is a schematic view of an example of a portion of the CO₂ separation system of the present disclosure performing a third mode.

FIG. 4 is a schematic view of another example of the CO₂ separation system of the present disclosure, which can perform the first mode, the second mode, and the third mode.

FIG. 5 is a schematic view of yet another example of the CO₂ separation system of the present disclosure, which can perform the first mode, the second mode, and the third mode.

DESCRIPTION OF EMBODIMENTS

The embodiments of the present disclosure will be described in detail below. Note that the present disclosure is not limited to the following embodiments. Various modifications can be made within the scope of the gist of the present disclosure.

<<CO₂ Separation System>>

The CO₂ separation system of the present disclosure is a CO₂ separation system for installation in a vehicle using an internal combustion engine as a power source. The CO₂ separation system of the present disclosure comprises an internal combustion engine, a first CO₂ separation device including a CO₂ permeable membrane separating a CO₂ supply side and a CO₂ permeation side, a first CO₂ supply side introduction flow path for introducing exhaust gas generated by the internal combustion engine to the CO₂ supply side of the first CO₂ separation device, and a first CO₂ permeation side introduction flow path for introducing air from outside the vehicle to the CO₂ permeation side of the first CO₂ separation device.

The CO₂ separation system of the present disclosure:

(A) performs, when the internal combustion engine is operating and the vehicle is travelling, a first mode wherein exhaust gas generated by the internal combustion engine is introduced to the CO₂ supply side of the first CO₂ separation device via the first CO₂ supply side introduction flow path, and air from outside the vehicle is introduced to the CO₂ permeation side of the first CO₂ separation device via the first CO₂ permeation side introduction flow path using travelling wind, whereby CO₂ in the exhaust gas selectively permeates from the CO₂ supply side to the CO₂ permeation side of the first CO₂ separation device through the CO₂ permeable membrane of the first CO₂ separation device using a difference in CO₂ partial pressure between the CO₂ supply side and the CO₂ permeation side of the first CO₂ separation device as a driving force.

Note that in the present description, “travelling wind” means an air flow occurring relatively between the vehicle and the outside of the vehicle when the vehicle is travelling.

The CO₂ separated by the CO₂ separation system of the present disclosure can be decomposed using, for example, a plasma and discharged as C and O₂.

Separated CO₂ can also be recovered and used as a material for synthesizing hydrocarbons. The synthesized hydrocarbons can be reused as fuel for internal combustion engines. As a method of synthesizing hydrocarbons from CO₂, for example, a method of synthesizing hydrocarbons using H₂ produced by electrolyzing water in exhaust gas, or a method of introducing CO₂ together with a reactor into water to produce hydrocarbons by artificial photosynthesis can be used.

<First Mode>

The CO₂ separation system of the present disclosure (A) performs the above first mode when the internal combustion engine is operating and the vehicle is travelling.

FIG. 1 is a schematic view of an example of a portion of the CO₂ separation system of the present disclosure performing the first mode. Though not explicitly shown in FIG. 1, the internal combustion engine is operating and the vehicle is travelling.

In FIG. 1, the exhaust gas discharged from the internal combustion engine 100 is introduced to the CO₂ supply side 311 of the first CO₂ separation device 310 via a first CO₂ supply side introduction flow path 410, as indicated by the arrow. Furthermore, air from outside 200 of the vehicle, powered by travelling wind, is supplied to the CO₂ permeation side 312 of the first CO₂ separation device 310 via the first CO₂ permeation side introduction flow path 420, as indicated by the arrow. As a result, exhaust gas is present on the CO₂ supply side 311 of the first CO₂ separation device 310 and air is present on the CO₂ permeation side 312.

The partial pressure of the CO₂ in the exhaust gas is higher than the partial pressure of the CO₂ in the air. Further, due to Bernoulli's theorem, the static pressure of CO₂ is reduced on the CO₂ permeation side by the traveling wind, and thus, there is a difference in CO₂ partial pressure between the CO₂ supply side and CO₂ permeation side of the first CO₂ separation device 310.

Using this difference in CO₂ partial pressure as a driving force, CO₂ in the exhaust gas 10 permeates from the CO₂ supply side 311 to the CO₂ permeation side 312 via the CO₂ permeable membrane 313, as indicated by the arrow.

The CO₂ which permeates to the CO₂ permeation side 312 is discharged to the outside of the first CO₂ separation device 310 along with air via the first CO₂ permeation side discharge flow path 425, as indicated by the arrow. Furthermore, the remaining components of the exhaust gas introduced to the CO₂ supply side 311 of the first CO₂ separation device 310 flow along the first CO₂ supply side discharge flow path 415 and are discharged to the outside of the first CO₂ separation device 310, as indicated by the arrow.

Note that FIG. 1 is not intended to limit the CO₂ separation system of the present invention to an aspect including a first CO₂ supply side discharge flow path 415 and a first CO₂ permeation side discharge flow path 425.

Thus, in the first mode, CO₂ on the CO₂ permeation side can be more efficiently separated using the difference in CO₂ partial pressure between the CO₂ supply side and the CO₂ permeation side of the first CO₂ separation device.

<Second Mode and Third Mode>

The CO₂ separation system of the present disclosure can further perform the following second mode and third mode depending on the state of the vehicle.

(Second Mode)

The CO₂ separation system of the present disclosure (B) may perform the second mode when the internal combustion engine is operating and the vehicle is stopped. When the CO₂ separation system of the present disclosure performs the second mode, the CO₂ separation system of the present disclosure further includes a first decompression device.

In the second mode, exhaust gas generated by the internal combustion engine is introduced to the CO₂ supply side of the first CO₂ separation device via the first CO₂ supply side introduction flow path and the CO₂ permeation side of the first CO₂ separation device is decompressed by the first decompression device, whereby CO₂ in the exhaust gas selectively permeates from the CO₂ supply side to the CO₂ permeation side of the first CO₂ separation device through the CO₂ permeable membrane of the first CO₂ separation device using the difference in CO₂ partial pressure between the CO₂ supply side and the CO₂ permeation side of the first CO₂ separation device as a driving force.

FIG. 2 is a schematic view of an example of a portion of the CO₂ separation system of the present disclosure performing the second mode. Though not explicitly shown in FIG. 2, the internal combustion engine is operating and the vehicle is stopped.

In FIG. 2, exhaust gas discharged from the internal combustion engine 100 is introduced to the CO₂ supply side 311 of the first CO₂ separation device 300, as indicated by the arrow. Furthermore, the CO₂ permeation side 312 of the first CO₂ separation device 310 is decompressed by the first decompression device 510. As a result, a difference in CO₂ partial pressure is generated between the CO₂ supply side 311 and the CO₂ permeation side 312.

Using this difference in partial pressure as a driving force, CO₂ in the exhaust gas permeates from the CO₂ supply side 311 to the CO₂ permeation side 312 via the CO₂ permeable membrane 313, as indicated by the arrow.

Since the CO₂ permeation side 312 is decompressed by the first decompression device 510 arranged in the first CO₂ permeation side discharge flow path 425, the CO₂ which has permeated to the CO₂ permeation side 312 can be efficiently discharged to the outside of the first CO₂ separation device 310 via the first CO₂ permeation side discharge flow path 425, as indicated by the arrow. Furthermore, the remaining components of the exhaust gas introduced to the CO₂ supply side 311 of the first CO₂ separation device 310 are discharged to the outside of the first CO₂ separation device 310 via the first CO₂ supply side discharge flow path 415, as indicated by the arrow.

Note that FIG. 2 is not intended to limit the CO₂ separation system of the present disclosure to an aspect including the first CO₂ supply side discharge flow path 415 and the first CO₂ permeation side discharge flow path 425. Furthermore, FIG. 2 is not intended to limit the CO₂ separation system of the present disclosure to an aspect in which the power for discharging the CO₂ to the outside of the first CO₂ separation device 310 is imparted by the first decompression device 510.

Thus, in the second mode, CO₂ on the CO₂ permeation side can be more efficiently separated using the CO₂ partial pressure of the CO₂ supply side and the CO₂ permeation side of the CO₂ separation device.

CO₂ in the exhaust gas of a vehicle using an internal combustion engine as a power source can be more efficiently separated when the CO₂ separation system of the present disclosure performs the second mode in addition to the first mode.

(Third Mode)

The CO₂ separation system of the present disclosure (C) can further perform a third mode when the internal combustion engine is stopped. When the CO₂ separation system of the present disclosure performs the third mode, the CO₂ separation system further comprises a second CO₂ separation device comprising a CO₂ permeable membrane separating a CO₂ supply side and a CO₂ permeation side, a second CO₂ supply side introduction flow path for introducing air from outside the vehicle to the CO₂ supply side of the second CO₂ separation device, and a second decompression device for decompressing the CO₂ permeation side of the second CO₂ separation device.

In the third mode, air from outside the vehicle is introduced to the CO₂ supply side of the second CO₂ separation device via the second CO₂ supply side introduction flow path, and the CO₂ permeation side of the second CO₂ separation device is decompressed by the second decompression device, whereby CO₂ in the air selectively permeates from the CO₂ supply side to the CO₂ permeation side of the second CO₂ separation device through the CO₂ permeable membrane of the second CO₂ separation device using a difference in CO₂ partial pressure between the CO₂ supply side and the CO₂ permeation side of the second CO₂ separation device as a drive force.

FIG. 3 is a schematic view of an example of a portion of the CO₂ separation system of the present disclosure performing the third mode. Though not explicitly shown in FIG. 3, the internal combustion engine is stopped. The vehicle may be travelling or may be stopped.

In FIG. 3, air introduced from outside 200 of the vehicle is introduced to the CO₂ supply side 321 of the second CO₂ separation device 320 via the second CO₂ supply side introduction flow path 430, as indicated by the arrow. Furthermore, the CO₂ permeation side 322 of the second CO₂ separation device 320 is decompressed by the second decompression device 520. As a result, a difference in CO₂ partial pressure is generated between the CO₂ supply side 321 and the CO₂ permeation side 322.

Using this difference in partial pressure as a driving force, CO₂ in the air permeates from the CO₂ supply side 321 to the CO₂ permeation side 322 via the CO₂ permeable membrane 323.

Since the CO₂ permeation side 322 is decompressed by the second decompression device 520 arranged in the second CO₂ permeation side discharge flow path 445, CO₂ permeated from the CO₂ permeation side 322 is efficiently discharged to the outside of the second CO₂ separation device 320 via the first CO₂ permeation side discharge flow path 445, as indicated by the arrow. Furthermore, the remaining components of the air introduced to the CO₂ supply side 321 are discharged to the outside of the second CO₂ separation device 320 via the second CO₂ supply side discharge flow path 435, as indicated by the arrow.

Furthermore, FIG. 3 is not intended to limit the CO₂ separation system of the present disclosure to an aspect including a second CO₂ supply side discharge flow path 435 and a second CO₂ permeation side discharge flow path 445. Furthermore, FIG. 3 is not intended to limit the CO₂ separation system of the present disclosure to an aspect in which the power for discharging the CO₂ to the outside of the second CO₂ separation device 320 is imparted by the second decompression device 520.

Thus, in the third mode, CO₂ can be more efficiently separated on the CO₂ permeation side using the CO₂ partial pressure between the CO₂ supply side and CO₂ permeation side of the CO₂ separation device.

Furthermore, when the CO₂ separation system of the present disclosure performs the third mode in addition to the first mode, not only CO₂ in the exhaust gas of a vehicle using an internal combustion engine as a power source, but also CO₂ in the atmosphere surrounding the roadway can be separated.

<Vehicle>

The vehicle in which the CO₂ separation system of the present disclosure is installed is a vehicle using an internal combustion engine as a power source. The vehicle in which the CO₂ separation system of the present disclosure in installed may be a hybrid vehicle further comprising an electric motor, wherein at least one of the internal combustion engine and the electric motor is switched on and used as a power source.

In the case where the CO₂ separation system of the present disclosure is installed in such a hybrid vehicle, when the internal combustion engine of the vehicle is stopped and the vehicle is travelling using the electric motor, the third mode can be performed, whereby CO₂ in the atmosphere surrounding the roadway can be more efficiently separated. In this case, the difference in CO₂ partial pressure between the CO₂ supply side and the CO₂ permeation side of the second CO₂ separation device can be a result of Bernoulli's theorem by lowering the static pressure of the CO₂ on the CO₂ permeation side by the traveling wind, in addition to, or in place thereof to the decompression of the CO₂ permeation side of the second CO₂ separation device by the second decompression device.

<CO₂ Separation Device>

The CO₂ separation system of the present disclosure includes a first CO₂ separation device. The first CO₂ separation device includes a CO₂ permeable membrane separating a CO₂ supply side and a CO₂ permeation side.

The CO₂ permeable membrane included in the first CO₂ separation device is not particularly limited as long as CO₂ from exhaust gas can selectively permeate therethrough. In the first and second modes, from the viewpoint of using the CO₂ permeable membrane to separate CO₂ from the exhaust gas, the CO₂ permeable membrane is preferably a zeolite membrane, a silica membrane, or the like. These permeable membranes are preferable due to their high mechanical durability.

Furthermore, when the CO₂ separation system of the present disclosure performs the third mode, the CO₂ separation system of the present disclosure comprises a second CO₂ separation device. The second CO₂ separation device includes a CO₂ permeable membrane for separating a CO₂ supply side and a CO₂ permeable side.

The CO₂ permeable membrane included in the second CO₂ separation device is not particularly limited as long as CO₂ in air can selectively permeate therethrough. In the third mode, from the viewpoint of using the CO₂ permeable membrane for separating CO₂ from air, it is preferable to use a permeable membrane which can separate with high efficiency even when the partial pressure difference is relatively small, such as a polymer membrane, as the CO₂ permeable membrane.

In the case in which the CO₂ separation system of the present disclosure performs the first through third modes, the first CO₂ separation device used in the first mode and the second mode and the second CO₂ separation device used in the third mode can be separate devices or can be the same device. In this case, a CO₂ permeable membrane through which CO₂ in air and exhaust gas can permeate is used as the CO₂ permeable membrane included in the CO₂ separation device.

When the first CO₂ separation device used in the first mode and the second mode and the second CO₂ separation device used in the third mode are separate devices, a CO₂ permeable membrane suitable for the permeation of CO₂ in exhaust gas can be used in the first CO₂ separation device used in the first mode and the second mode and a CO₂ permeable membrane suitable for the permeation of CO₂ in air can be used in the second CO₂ separation device used in the third mode. Thus, the CO₂ permeable membrane used for the permeation of CO₂ can be switched in accordance with the mode, and CO₂ separation can be efficiently performed.

Furthermore, when the first CO₂ separation device used in the first mode and the second mode and the second CO₂ separation device used in the third mode are the same device, the space necessary for installation of the CO₂ separation system of the present disclosure can be reduced, and it is possible to save space in the vehicle in which the CO₂ separation system of the present disclosure is installed.

<Flow Path>

The CO₂ separation system of the present disclosure includes a first CO₂ supply side introduction flow path for introducing exhaust gas generated by the internal combustion engine to the CO₂ supply side of the first CO₂ separation device and a first CO₂ permeation side introduction flow path for introducing air from outside of the vehicle to the CO₂ permeation side of the first CO₂ separation device.

The shape of the first CO₂ supply side introduction flow path is not particularly limited as long as exhaust gas generated by the internal combustion engine can be introduced to the CO₂ supply side of the first CO₂ separation device thereby. The first CO₂ supply side introduction flow path can have, for example, a pipe-like shape connecting the internal combustion engine and the CO₂ supply side of the first CO₂ separation device.

The shape of the first CO₂ permeation side introduction flow path is not particularly limited as long as air from outside of the vehicle can be introduced to the CO₂ permeation side of the first CO₂ separation device thereby. The first CO₂ permeation side introduction flow path can have, for example, a pipe-like shape connecting the outside of the vehicle and the CO₂ permeation side of the first CO₂ separation device.

In the CO₂ separation system of the present disclosure, if the system performs the third mode, the CO₂ separation system includes a second CO₂ supply side introduction flow path for introducing air from outside of the vehicle to the CO₂ supply side of the second CO₂ separation device.

The shape of the second CO₂ supply side introduction flow path is not particularly limited as long as air from outside of the vehicle can be introduced to the CO₂ supply side of the second CO₂ separation device thereby. The second CO₂ supply side introduction flow path can have, for example, a pipe-like shape connecting the outside of the vehicle and the CO₂ supply side of the second CO₂ separation device.

When the first CO₂ separation device used in the first mode and the second mode and the second CO₂ separation device used in the third mode are the same device, the first CO₂ supply side introduction flow path and the second CO₂ supply side introduction flow path may be the same flow path.

When the first CO₂ supply side introduction flow path and the second CO₂ supply side introduction flow path are the same flow path, the CO₂ supply side introduction flow path can have, for example, a branched pipe-like structure on the side opposite the CO₂ separation device side. The branched piping may have a configuration wherein one of the branched pipes connects the internal combustion engine with the CO₂ separation devices and the other pipe connects the outside of the vehicle with the CO₂ separation devices.

Further, the branched piping may have a configuration wherein a switching device such as valve is provided in the pipe that connects the outside of the vehicle with the CO₂ separation device, whereby the gas to be introduced to the CO₂ supply side of the CO₂ separation device can be switched in accordance with the mode.

<Decompression Device>

In the CO₂ separation system of the present disclosure, when the second and third modes are performed, the CO₂ separation system includes first and second decompression devices. Any known decompression device can be used. For example, a decompression pump can be used as the decompression device.

When the second and third modes are performed, the decompression devices are used to decompress the CO₂ permeation sides of the CO₂ separation devices. Furthermore, the decompression devices can be used as the power source for discharging CO₂ which has permeated to the CO₂ permeation side to the outside of the CO₂ separation device.

The first decompression device and the second decompression device may be the same device or may be separate devices.

CONFIGURATION EXAMPLES

The CO₂ separation device of the present disclosure may have, for example, the configurations shown below. Note that these configurations do not limit the aspects of the CO₂ separation system of the present disclosure.

Configuration Example 1

FIG. 4 is a schematic view of another example of the CO₂ separation system of the present disclosure, which can perform the first mode, the second mode, and the third mode.

In FIG. 4, the CO₂ separation system comprises an internal combustion engine 100, a first CO₂ separation device 310, a first CO₂ supply side introduction flow path 410, a first CO₂ permeation side introduction flow path 420, a second CO₂ separation device 320, a second CO₂ supply side introduction flow path 430, and a decompression device 500.

The first CO₂ separation device 310 comprises a CO₂ permeable membrane 313 for separating the CO₂ supply side 311 and the CO₂ permeation side 312. Furthermore, the second CO₂ separation device 320 comprises a CO₂ permeable membrane 323 which separates the CO₂ supply side 321 and the CO₂ permeation side 322.

The first CO₂ supply side introduction flow path 410 connects the internal combustion engine 100 and the CO₂ supply side 311 of the first CO₂ separation device 310. Furthermore, the first CO₂ permeation side introduction flow path 420 connects the outside 200 of the vehicle and the CO₂ permeation side 312 of the first CO₂ separation device 310. Moreover, the second CO₂ supply side introduction flow path 430 connects the outside 200 of the vehicle and the CO₂ supply side 321 of the second CO₂ separation device 320.

In FIG. 4, the CO₂ separation system is further provided, in the first CO₂ permeation side introduction flow path 420 on the side opposite the first CO₂ separation device 310 side, with a valve 801 which can adjust the amount of air introduced from the outside 200 of the vehicle. Furthermore, a valve 802 which can adjust the amount of air introduced from outside 200 of the vehicle is provided in the second CO₂ supply side introduction flow path 430 on the side opposite the second CO₂ separation device 320 side.

Furthermore, in FIG. 4, the CO₂ separation system further comprises a catalytic device for exhaust gas purification 600, a first CO₂ supply side discharge flow path 415, a first CO₂ permeation side discharge flow path 425, a second CO₂ supply side discharge flow path 435, a second CO₂ permeation side discharge flow path 445, and a CO₂ storage device 700.

In the CO₂ separation system of FIG. 4, when the first mode is performed, the CO₂ separation system of the present disclosure functions as follows.

After the exhaust gas generated by the internal combustion engine 100 has passed through the catalytic device for exhaust gas purification 600, the exhaust gas is introduced to the CO₂ supply side 311 of the first CO₂ separation device 310 via the first CO₂ supply side introduction flow path 410. Furthermore, the valve 801 is opened, air from outside 200 of the vehicle is drawn into the vehicle by, for example, travelling wind, and the air is supplied to the CO₂ permeation side 312 of the first CO₂ separation device 310 via the first CO₂ permeation side introduction flow path 420.

As a result, exhaust gas is introduced to the CO₂ supply side 311 of the first CO₂ separation device 310 and air is introduced to the CO₂ permeation side 312, whereby a CO₂ partial pressure is generated between the CO₂ supply side 311 and the CO₂ permeation side 312 of the first CO₂ separation device 310.

Using this difference in partial pressure as a driving force, CO₂ in the exhaust gas permeates from the CO₂ supply side 311 to the CO₂ permeation side 312 via the CO₂ permeable membrane 313.

The CO₂ which has permeated to the CO₂ permeation side 312 is discharged to the outside of the first CO₂ separation device 310 along with air via the first CO₂ permeation side discharge flow path 425 and is stored in the CO₂ storage device 700.

When the second mode is performed by using the system described FIG. 4, the CO₂ separation system of the present disclosure functions as follows.

After the exhaust gas generated by the internal combustion engine 100 has passed through the catalytic device for exhaust gas purification 600, the exhaust gas is introduced to the CO₂ supply side 311 of the first separation device 310 via the first CO₂ supply side introduction flow path 410. At this time, the valve 801 is closed.

The CO₂ permeation side 312 of the first CO₂ separation device 310 is decompressed by the decompression device 500. As a result, a CO₂ partial pressure is generated between the CO₂ supply side 311 and the CO₂ permeation side 312 of the first CO₂ separation device.

Using this difference in partial pressure as a driving force, CO₂ in the exhaust gas permeates to the CO₂ permeation side 312 from the CO₂ supply side 311 via the CO₂ permeable membrane 313.

The CO₂ which has permeated to the CO₂ permeation side 312 is discharged to the outside of the first CO₂ separation device 310 along with air via the first CO₂ permeation side discharge flow path 425 and is stored in the CO₂ storage device 700.

When the third mode is performed by using the CO₂ separation system of FIG. 4, the CO₂ separation system of the present disclosure functions as follows.

The valve 802 provided in the second CO₂ supply side introduction flow path 430 on the side opposite the second CO₂ separation device 320 is opened, whereby air is introduced from the outside 200 of the vehicles to the CO₂ supply side 321 of the second CO₂ separation device 320 via the second supply side introduction flow path 430. Furthermore, the CO₂ permeation side 322 of the second CO₂ separation device 320 is decompressed by the decompression device 500.

As a result, a difference in CO₂ partial pressure is generated between the CO₂ supply side 321 and the CO₂ permeation side 322 of the second CO₂ separation device 320. Using this difference in partial pressure as a driving force, CO₂ in the air permeates from the CO₂ supply side 321 to the CO₂ permeation side 322 via the CO₂ permeable membrane 323. The CO₂ which has permeated to the CO₂ permeation side 322 is discharged to the outside of the second CO₂ separation device via the second CO₂ permeation side discharge flow path 445 and is stored in the CO₂ storage device 700.

Configuration Example 2

FIG. 5 is a schematic view of another example of the CO₂ separation system of the present disclosure, which can perform the first mode, the second mode, and the third mode.

The CO₂ separation system of FIG. 5 has a configuration wherein the first CO₂ separation device and the second CO₂ separation device are the same device, the first CO₂ supply side introduction flow path and the second CO₂ supply side introduction flow path are the same flow path, and the first decompression device and the second decompression device are the same device.

In FIG. 5, the CO₂ separation system comprises an internal combustion engine 100, a first CO₂ separation device 310, a first CO₂ supply side introduction flow path 410, a first CO₂ permeation side introduction flow path 420, and a decompression device 500.

The first CO₂ separation device 310 comprises a CO₂ permeable membrane 323 which separates the CO₂ supply side 311 and the CO₂ permeation side 312. The first CO₂ supply side introduction flow path 410 connects the internal combustion engine 100 with the CO₂ supply side 311 of the first CO₂ separation device 310 and connects the outside 200 of the vehicle with the CO₂ supply side 311 of the first CO₂ separation device 310. Furthermore, the first CO₂ permeation side introduction flow path 420 connects the outside 200 of the vehicle with the CO₂ permeation side 312 of the first CO₂ separation device 310.

Further, the valve 801 and the valve 802 are provided in the first CO₂ supply side introduction flow path 410 on the side of the outside 200 of the vehicle and the first CO₂ permeation side introduction flow path 420 on the side of the outside 200 of the vehicle, respectively. By opening and closing these two valves, the introduction of air from outside 200 of the vehicle can be switched between the CO₂ supply side 311 and the CO₂ permeation side 312 of the first CO₂ separation device 310.

Furthermore, in FIG. 5, the CO₂ separation system further comprises a catalytic device for exhaust gas purification 600, a first CO₂ supply side discharge flow path 415, a first CO₂ permeation side discharge flow path 425, and a CO₂ storage device 700. A decompression device 500 is provided in the first CO₂ permeation side discharge flow path 425 on the side opposite the first CO₂ separation device 310.

Like the CO₂ separation system of FIG. 4, the CO₂ separation system of FIG. 5 can perform the first mode, the second mode, and the third mode by opening and closing the valves depending on whether the internal combustion engine is operating or stopped and whether or not the vehicle is travelling.

REFERENCE SIGNS LIST

-   -   100 internal combustion engine     -   200 outside of the vehicle     -   310 first CO₂ separation device     -   311 CO₂ supply side     -   312 CO₂ permeation side     -   313 CO₂ permeable membrane     -   320 second CO₂ separation device     -   321 CO₂ supply side     -   322 CO₂ permeation side     -   323 CO₂ permeable membrane     -   410 first CO₂ supply side introduction flow path     -   415 first CO₂ supply side discharge flow path     -   420 first CO₂ permeation side introduction flow path     -   425 first CO₂ permeation side discharge flow path     -   430 second CO₂ supply side introduction flow path     -   435 second CO₂ supply side discharge flow path     -   445 second CO₂ permeation side discharge flow path     -   500 decompression device     -   510 first decompression device     -   520 second decompression device     -   600 catalytic device for exhaust gas purification     -   700 CO₂ storage device     -   801 valve     -   802 valve 

The invention claimed is:
 1. A CO₂ separation method using a system for installation in a vehicle using an internal combustion engine as a power source, the system comprising the internal combustion engine, a first CO₂ separation device comprising a CO₂ permeable membrane separating a CO₂ supply side and a CO₂ permeation side, a first CO₂ supply side introduction flow path for introducing exhaust gas generated by the internal combustion engine to the CO₂ supply side of the first CO₂ separation device, a first CO₂ permeation side introduction flow path for introducing air from outside the vehicle to the CO₂ permeation side of the first CO₂ separation device, and a first decompression pump for decompressing the CO₂ permeation side of the first CO₂ separation device, the method comprising performing: (A) when the internal combustion engine is operating and the vehicle is travelling, a first mode wherein exhaust gas generated by the internal combustion engine is introduced to the CO₂ supply side of the first CO₂ separation device via the first CO₂ supply side introduction flow path, and air from outside the vehicle is introduced to the CO₂ permeation side of the first CO₂ separation device via the first CO₂ permeation side introduction flow path using travelling wind, whereby CO₂ in the exhaust gas selectively permeates from the CO₂ supply side to the CO₂ permeation side of the first CO₂ separation device through the CO₂ permeable membrane of the first CO₂ separation device, using a first difference in CO₂ partial pressure between the CO₂ supply side and the CO₂ permeation side of the first CO₂ separation device as a first driving force, and (B) when the internal combustion engine is operating and the vehicle is stopped, a second mode wherein exhaust gas generated by the internal combustion engine is introduced to the CO₂ supply side of the first CO₂ separation device via the first CO₂ supply side introduction flow path and the CO₂ permeation side of the first CO₂ separation device is decompressed by the first decompression pump, whereby CO₂ in the exhaust gas selectively permeates from the CO₂ supply side to the CO₂ permeation side of the first CO₂ separation device through the CO₂ permeable membrane of the first CO₂ separation device, using a second difference in CO₂ partial pressure between the CO₂ supply side and the CO₂ permeation side of the first CO₂ separation device as a second driving force.
 2. The method according to claim 1, wherein the system further comprises a second CO₂ separation device comprising a CO₂ permeable membrane for separating a CO₂ supply side and a CO₂ permeation side, a second CO₂ supply side introduction flow path for introducing air from outside the vehicle to the CO₂ supply side of the second CO₂ separation device, and a second decompression pump for decompressing the CO₂ permeation side of the second CO₂ separation device, and the method further comprises performing (C) when the internal combustion engine is stopped, a third mode wherein air from outside the vehicle is introduced to the CO₂ supply side of the second CO₂ separation device via the second CO₂ supply side introduction flow path, and the CO₂ permeation side of the second CO₂ separation device is decompressed by the second decompression pump, whereby CO₂ in the air selectively permeates from the CO₂ supply side to the CO₂ permeation side of the second CO₂ separation device through the CO₂ permeable membrane of the second CO₂ separation device using a third difference in CO₂ partial pressure between the CO₂ supply side and the CO₂ permeation side of the second CO₂ separation device as a third drive force.
 3. The method according to claim 2, wherein the first CO₂ separation device and the second CO₂ separation device are the same device, the first CO₂ supply side introduction flow path and the second CO₂ supply side introduction flow path are the same flow path, and the first decompression pump and the second decompression pump are the same pump.
 4. The method according to claim 1, wherein the vehicle is a hybrid vehicle further comprising an electric motor, wherein at least one of the internal combustion engine and the electric motor is switched on and used as a power source. 